@article{MTMT:32599815, title = {Q-Bot: automatic DICOM metadata monitoring for the next level of quality management in nuclear medicine}, url = {https://m2.mtmt.hu/api/publication/32599815}, author = {Nagy, Ferenc and Krizsán, Áron Krisztián and Kukuts, Kornel and Szolikova, Melinda and Hasesi, Zsolt and Barna, Sándor Kristóf and Acs, Antonietta and Szabo, Peter and Trón, Lajos and Balkay, László and Dahlbom, Magnus and Zentai, Mihaly and Forgács, Attila and Garai, Ildikó}, doi = {10.1186/s40658-021-00371-w}, journal-iso = {EJNMMI PHYS}, journal = {EJNMMI PHYSICS}, volume = {8}, unique-id = {32599815}, issn = {2197-7364}, abstract = {Background Regular and precise inspection of the realization of the local nuclear medicine standard operation procedures (SOPs) is very complex and time-consuming, especially when large amount of patient data is obtained from a wide scale of different scan procedures on a daily basis. DICOM metadata comprise a complete set of data related to the patient and the imaging procedure, and consequently all information necessary to evaluate the compliance with the actual SOP. Methods Q-Bot, an automatic DICOM metadata monitoring tool which is capable to verify SOP conformities, was tested for 11 months at two nuclear medicine departments. Relevant parameters, such as patient ID, patient mass and height, injected activity, and uptake time, were investigated in the case of adult F-18-FDG whole-body PET/CT and Tc-99m-MDP gamma camera bone scans on a daily basis. Q-Bot automatically inspected the actual SOP compliance of these relevant DICOM parameters. Q-Bot graphical user interface (GUI) provided a summary of the outliers in a table format to be investigated by a dedicated technologist. In addition, information related to the error handling was also collected for retrospective analysis of long-term tendencies. Results In total, 6702 PET/CT and 2502 gamma camera scans were inspected, from which 8581 were confirmed as valid patient study without errors. Discrepancies related to the lack of a parameter, not appropriate format, or improper scan procedures were found in 623 cases, and 156 out of these were corrected before the medical reading and reporting. SOP non-conformities explored with Q-Bot were found to be non-correctable in 467 cases. Systematic errors to our practice turned out to be the manual radiopharmaceutical injection, the allowance to use both SI and non-SI units, and the clear definition of decimal point symbol to use. Conclusion The daily evaluation of Q-Bot results provided early detection of errors and consequently ensured the minimization of error propagation. Integration of a QM software that inspects protocol compliance at a nuclear medicine department provides significant support to detect non-conformities for technologists, and much higher confidence in image quality for physicians.}, keywords = {CT; Quality Management; F-18-FDG PET; protocol compliance; DICOM metadata; Tc-99m-MDP Bone Scan}, year = {2021}, eissn = {2197-7364}, orcid-numbers = {Nagy, Ferenc/0000-0002-6469-7957} } @article{MTMT:31336784, title = {OAR sparing 3D radiotherapy planning supported by fMRI brain mapping investigations}, url = {https://m2.mtmt.hu/api/publication/31336784}, author = {Opposits, Gábor and Aranyi, Sándor Csaba and Glavák, Csaba and Cselik, Zsolt and Trón, Lajos and Sipos, Dávid and Hadjiev, Janaki and Berényi, Ervin László and Repa, Imre and Emri, Miklós and Kovács, Árpád}, doi = {10.1016/j.meddos.2020.04.003}, journal-iso = {MED DOSIM}, journal = {MEDICAL DOSIMETRY}, volume = {45}, unique-id = {31336784}, issn = {0958-3947}, year = {2020}, eissn = {1873-4022}, pages = {e1-e8}, orcid-numbers = {Aranyi, Sándor Csaba/0000-0001-9569-5404; Glavák, Csaba/0000-0003-1448-810X; Cselik, Zsolt/0000-0003-2090-4632; Sipos, Dávid/0000-0001-9615-1740; Hadjiev, Janaki/0000-0003-4419-353X; Kovács, Árpád/0000-0002-8469-5764} } @article{MTMT:30418465, title = {Activity Painting: PET images of freely defined activity distributions applying a novel phantom technique}, url = {https://m2.mtmt.hu/api/publication/30418465}, author = {Forgács, Attila and Kallos-Balogh, Piroska and Nagy, Ferenc and Krizsán, Áron Krisztián and Garai, Ildikó and Trón, Lajos and Dahlbom, Magnus and Balkay, László}, doi = {10.1371/journal.pone.0207658}, journal-iso = {PLOS ONE}, journal = {PLOS ONE}, volume = {14}, unique-id = {30418465}, issn = {1932-6203}, abstract = {The aim of this work was to develop a novel phantom that supports the construction of highly reproducible phantoms with arbitrary activity distributions for PET imaging. It could offer a methodology for answering questions related to texture measurements in PET imaging. The basic idea is to move a point source on a 3-D trajectory in the field of view, while continuously acquiring data. The reconstruction results in a 3-D activity concentration map according to the pathway of the point source. A Na-22 calibration point source was attached to a high precision robotic arm system, where the 3-D movement was software controlled. 3-D activity distributions of a homogeneous cube, a sphere, a spherical shell and a heart shape were simulated. These distributions were used to measure uniformity and to characterize reproducibility. Two potential applications using the lesion simulation method are presented: evaluation in changes of textural properties related to the position in the PET field of view; scanner comparison based on visual and quantitative evaluation of texture features. A lesion with volume of 50x50x50 mm(3) can be simulated during approximately 1 hour. The reproducibility of the movement was found to be >99%. The coefficients of variation of the voxels within a simulated homogeneous cube was 2.34%. Based on 5 consecutive and independent measurements of a 36 mm diameter hot sphere, the coefficient of variation of the mean activity concentration was 0.68%. We obtained up to 18% differences within the values of investigated textural indexes, when measuring a lesion in different radial positions of the PET field of view. In comparison of two different human PET scanners the percentage differences between heterogeneity parameters were in the range of 5-55%. After harmonizing the voxel sizes this range reduced to 2-16%. The general activity distributions provided by the two different vendor show high similarity visually. For the demonstration of the flexibility of this method, the same pattern was also simulated on a small animal PET scanner giving similar results, both quantitatively and visually. 3-D motion of a point source in the PET field of view is capable to create an irregular shaped activity distribution with high reproducibility.}, year = {2019}, eissn = {1932-6203}, pages = {1-15} } @article{MTMT:3125467, title = {A Study on the Basic Criteria for Selecting Heterogeneity Parameters of F18-FDG PET Images.}, url = {https://m2.mtmt.hu/api/publication/3125467}, author = {Forgács, Attila and Jonsson, H P and Dahlbom, M and Daver, F and DiFranco, M D and Opposits, Gábor and Krizsán, Áron Krisztián and Garai, Ildikó and Czernin, J and Varga, József and Trón, Lajos and Balkay, László}, doi = {10.1371/journal.pone.0164113}, journal-iso = {PLOS ONE}, journal = {PLOS ONE}, volume = {11}, unique-id = {3125467}, issn = {1932-6203}, abstract = {Textural analysis might give new insights into the quantitative characterization of metabolically active tumors. More than thirty textural parameters have been investigated in former F18-FDG studies already. The purpose of the paper is to declare basic requirements as a selection strategy to identify the most appropriate heterogeneity parameters to measure textural features. Our predefined requirements were: a reliable heterogeneity parameter has to be volume independent, reproducible, and suitable for expressing quantitatively the degree of heterogeneity. Based on this criteria, we compared various suggested measures of homogeneity. A homogeneous cylindrical phantom was measured on three different PET/CT scanners using the commonly used protocol. In addition, a custom-made inhomogeneous tumor insert placed into the NEMA image quality phantom was imaged with a set of acquisition times and several different reconstruction protocols. PET data of 65 patients with proven lung lesions were retrospectively analyzed as well. Four heterogeneity parameters out of 27 were found as the most attractive ones to characterize the textural properties of metabolically active tumors in FDG PET images. These four parameters included Entropy, Contrast, Correlation, and Coefficient of Variation. These parameters were independent of delineated tumor volume (bigger than 25-30 ml), provided reproducible values (relative standard deviation<10%), and showed high sensitivity to changes in heterogeneity. Phantom measurements are a viable way to test the reliability of heterogeneity parameters that would be of interest to nuclear imaging clinicians.}, year = {2016}, eissn = {1932-6203} } @article{MTMT:2948571, title = {Population based ranking of frameless CT-MRI registration methods [Quantifizierung der Qualität von Methoden zur Registrierung von CT- und MRT-Bildern unter Verwendung von Bilddaten eines großen Patientenkollektivs]}, url = {https://m2.mtmt.hu/api/publication/2948571}, author = {Opposits, Gábor and Kis, Sándor Attila and Trón, Lajos and Berényi, Ervin László and Takács, Endre and Dobai, JG and Bognár, László and Szucs, B and Emri, Miklós}, doi = {10.1016/j.zemedi.2015.07.001}, journal-iso = {Z MED PHYS}, journal = {ZEITSCHRIFT FUR MEDIZINISCHE PHYSIK}, volume = {25}, unique-id = {2948571}, issn = {0939-3889}, abstract = {BACKGROUND: Clinical practice often requires simultaneous information obtained by two different imaging modalities. Registration algorithms are commonly used for this purpose. Automated procedures are very helpful in cases when the same kind of registration has to be performed on images of a high number of subjects. Radiotherapists would prefer to use the best automated method to assist therapy planning, however there are not accepted procedures for ranking the different registration algorithms. PURPOSE: We were interested in developing a method to measure the population level performance of CT-MRI registration algorithms by a parameter of values in the [0,1] interval. MATERIALS AND METHODS: Pairs of CT and MRI images were collected from 1051 subjects. Results of an automated registration were corrected manually until a radiologist and a neurosurgeon expert both accepted the result as good. This way 1051 registered MRI images were produced by the same pair of experts to be used as gold standards for the evaluation of the performance of other registration algorithms. Pearson correlation coefficient, mutual information, normalized mutual information, Kullback-Leibler divergence, L1 norm and square L2 norm (dis)similarity measures were tested for sensitivity to indicate the extent of (dis)similarity of a pair of individual mismatched images. RESULTS: The square Hellinger distance proved suitable to grade the performance of registration algorithms at population level providing the developers with a valuable tool to rank algorithms. CONCLUSIONS: The developed procedure provides an objective method to find the registration algorithm performing the best on the population level out of newly constructed or available preselected ones.}, year = {2015}, eissn = {1876-4436}, pages = {353-367} } @article{MTMT:2721452, title = {Excel2Genie: A Microsoft Excel application to improve the flexibility of the Genie-2000 Spectroscopic software.}, url = {https://m2.mtmt.hu/api/publication/2721452}, author = {Forgács, Attila and Balkay, László and Trón, Lajos and Raics, Péter}, doi = {10.1016/j.apradiso.2014.07.005}, journal-iso = {APPL RADIAT ISOTOPES}, journal = {APPLIED RADIATION AND ISOTOPES}, volume = {94}, unique-id = {2721452}, issn = {0969-8043}, abstract = {Excel2Genie, a simple and user-friendly Microsoft Excel interface, has been developed to the Genie-2000 Spectroscopic Software of Canberra Industries. This Excel application can directly control Canberra Multichannel Analyzer (MCA), process the acquired data and visualize them. Combination of Genie-2000 with Excel2Genie results in remarkably increased flexibility and a possibility to carry out repetitive data acquisitions even with changing parameters and more sophisticated analysis. The developed software package comprises three worksheets: display parameters and results of data acquisition, data analysis and mathematical operations carried out on the measured gamma spectra. At the same time it also allows control of these processes. Excel2Genie is freely available to assist gamma spectrum measurements and data evaluation by the interested Canberra users. With access to the Visual Basic Application (VBA) source code of this application users are enabled to modify the developed interface according to their intentions.}, keywords = {Nuclear spectroscopy; Repetitive data evaluation; Microsoft COM; Microsoft Excel; Genie-2000}, year = {2014}, eissn = {1872-9800}, pages = {77-81} } @article{MTMT:2586190, title = {Cold wall effect eliminating method to determine the contrast recovery coefficient for small animal PET scanners using the NEMA NU-4 image quality phantom.}, url = {https://m2.mtmt.hu/api/publication/2586190}, author = {Lajtos, Imre and Czernin, J and Dahlbom, M and Daver, F and Emri, Miklós and Farshchi-Heydari, S and Forgács, Attila and Hoh, CK and Jószai, István and Krizsán, Áron Krisztián and Lantos, J and Major, Péter and Molnár, József and Opposits, Gábor and Trón, Lajos and Vera, DR and Balkay, László}, doi = {10.1088/0031-9155/59/11/2727}, journal-iso = {PHYS MED BIOL}, journal = {PHYSICS IN MEDICINE AND BIOLOGY}, volume = {59}, unique-id = {2586190}, issn = {0031-9155}, abstract = {The contrast recovery coefficients (CRC) were evaluated for five different small animal PET scanners: GE Explore Vista, Genisys4, MiniPET-2, nanoScan PC and Siemens Inveon. The NEMA NU-4 2008 performance test with the suggested image quality phantom (NU4IQ) does not allow the determination of the CRC values for the hot regions in the phantom. This drawback of NU4IQ phantom motivated us to develop a new method for this purpose. The method includes special acquisition and reconstruction protocols using the original phantom, and results in an artificially merged image enabling the evaluation of CRC values. An advantageous feature of this method is that it stops the cold wall effect from distorting the CRC calculation. Our suggested protocol results in a set of CRC values contributing to the characterization of small animal PET scanners. GATE simulations were also performed to validate the new method and verify the evaluated CRC values. We also demonstrated that the numerical values of this parameter depend on the actual object contrast of the hot region(s) and this mainly comes from the spillover effect. This effect was also studied while analysing the background activity level around the hot rods. We revealed that the calculated background mean values depended on the target contrast in a scanner specific manner. Performing the artificially merged imaging procedure and additional simulations using the micro hollow sphere (MHS) phantom geometry, we also proved that the inactive wall around the hot spheres can have a remarkable impact on the calculated CRC. In conclusion, we have shown that the proposed artificial merging procedure and the commonly used NU4IQ phantom prescribed by the NEMA NU-4 can easily deliver reliable CRC data otherwise unavailable for the NU4IQ phantom in the conventional protocol or the MHS phantom.}, year = {2014}, eissn = {1361-6560}, pages = {2727-2746} } @article{MTMT:2522941, title = {A debreceni kisállat PET program eredményei: A MiniPET-1, MiniPET-2 és a MiniPET-3 kamerák leképezési tulajdonságai. (in Hung.) IME - Az egészségügyi vezetôk szaklapja. Képalkotó különszám 12 (2013)33-38}, url = {https://m2.mtmt.hu/api/publication/2522941}, author = {Lajtos, Imre and Emri, Miklós and Trón, Lajos and Kis, Sándor Attila and Opposits, Gábor and Márián, Teréz and Trencsényi, György and Mikecz, Pál and Spisák, Tamás and Krizsán, Áron Krisztián and Molnár, József and Hegyesi, Gyula and Kalinka, Gábor and Valastyán, Iván and Király, Beáta and Balkay, L}, journal-iso = {IME}, journal = {IME}, volume = {12}, unique-id = {2522941}, issn = {1588-6387}, year = {2013}, eissn = {1789-9974}, pages = {33-38}, orcid-numbers = {Trencsényi, György/0000-0001-6456-6212} } @article{MTMT:2185221, title = {Performance evaluation and optimization of the MiniPET-II scanner}, url = {https://m2.mtmt.hu/api/publication/2185221}, author = {Lajtos, Imre and Emri, Miklós and Kis, Sándor Attila and Opposits, Gábor and Pótári, Norbert and Király, Beáta and Nagy, Ferenc and Trón, Lajos and Balkay, László}, doi = {10.1016/j.nima.2012.12.079}, journal-iso = {NUCL INSTRUM METH A}, journal = {NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, volume = {707}, unique-id = {2185221}, issn = {0168-9002}, keywords = {image quality; Preclinical imaging; NEMA; Coincidence time window; Small-animal PET scanner}, year = {2013}, eissn = {1872-9576}, pages = {26-34} } @article{MTMT:2326019, title = {Comparative analysis of image processing algorithms on quadratic and hexagonal grids}, url = {https://m2.mtmt.hu/api/publication/2326019}, author = {Kis, Sándor Attila and Opposits, Gábor and Lajtos, Imre and Spisák, Tamás and Balkay, László and Kovács, György and Trón, Lajos and Emri, Miklós}, journal-iso = {EUR J NUCL MED MOL I}, journal = {EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING}, volume = {38}, unique-id = {2326019}, issn = {1619-7070}, year = {2011}, eissn = {1619-7089}, pages = {S275-S275} }